The present invention is generally directed to novel polymers like semiconductor polymers and electronic devices thereof. More specifically, the present invention in embodiments is directed to electronic devices containing a class of novel semiconductor polymers comprised of a repeating segment containing at least one arylene with a long side chain, preferably an alkyl or an alkoxy chain containing from about 5 to about 25 carbon atoms, and one to about 10 aromatic heterocyclic units. These polymers are capable of molecular self-organization under appropriate conditions, providing ordered microstructures in thin films which are suitable for microelectronic device applications, particularly thin film transistors (TFTs). In embodiments of the present invention there are illustrated semiconductor polymers which are comprised of one or more arylene units with long side chains and one or more substituted and/or unsubstituted 2,5-thienylene (also referred to as 2,5-thiophenediyl) segments or units, and aryl, and referred to as thienylene-arylene polymers. The aforementioned long side chains impart solubility characteristics to the polymer, and when properly positioned on the polymer backbone, assist in inducing and facilitating molecular organization of the polymer. In TFT devices, highly ordered microstructures in the semiconductor channel layers are of value to the efficient charge carrier transport between the source and drain electrodes, thus the TFT performance.
Semiconductor polymers, such as certain polythiophenes, have been reported for use in TFTs. A number of these polymers have some solubility in organic solvents and can thus be processed in solution for fabricating the semiconductor channel layers in TFTs. Solution processes, such as spin coating, solution casting, dip coating, screen printing, stamp printing, jet printing and the like, have been utilized to fabricate TFT channel layers with these materials. Fabrication via common solution processes could render the TFT manufacture simpler and more economical as compared to the costly conventional photolithographic processes typical of silicon-based devices such as hydrogenated amorphous silicon TFTs. Moreover, polymer semiconductor materials, such as polythiophenes, enable fabrication of TFTs on flexible substrates such as plastic substrates. TFTs on flexible substrates could enable the design of electronic devices with structural flexibility and mechanical durability characteristics. The use of plastic substrates together with organic or polymer transistor components can transform the traditionally rigid silicon TFT structure into a mechanically durable and structurally flexible polymer TFT design, which is of particular value to large area devices such as large area image sensors, electronic paper and other display media. Also, the selection of polymer TFTs for integrated circuit elements for low-end microelectronics, such as smart cards, radio frequency identification (RFID) tags, and memory/storage devices, may also greatly enhance their mechanical durability, and thus their useful life span. However, a number of the semiconductor polythiophenes are not stable when exposed to air as they become oxidatively doped by ambient oxygen, resulting in increased conductivity. The result is large off current, lower current on/off ratio, and positive turn-on voltage for the p-type devices fabricated from these materials. Accordingly, with a number of these materials, rigorous precautions have to be undertaken during materials processing and device fabrication to exclude environmental oxygen to avoid or minimize oxidative doping. These precautionary measures add to the cost of manufacturing therefore offsetting the appeal of polymer TFTs as an economical alternative to amorphous silicon technology, particularly for large area devices. These and other disadvantages are avoided or minimized in embodiments of the present invention.